Eros Discussion

[jcmusic]

I am just kinda wondering why there hasn't been any talk here about the new product?

Jay

[Doc B.]

We don't have the kit version ready yet, as I need to finish writing the assembly manual. We have sold a few assembled ones. Perhaps the owners will share their impressions.

[ckniker]

Is the Assembly Manual the only thing holding up sales of the Eros Tape Preamp Kit?

If so, is it possible to order the parts now (without the Manual) and download the Manual when it's ready? I'd like to have the parts on hand and rearing to go.

Thanks in advance,
Chris

p.s. I just bought an Otari MX-5050 B2HD within the last week and I'm anxious to hear the improvements an external repro amp will make.

[Doc B.]

We are finishing up the assembly manual this week and I have put up an order page. There is no descriptive copy yet, just a photo. I should have the copy taken care of in the next day or two. In the meantime, if you want to get into the queue there's a live order button on the page -

http://www.bottlehead.com/store.php?crn=220&rn=440&action=show_detail

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.bottlehead.com%2Fsc_images%2Fproducts%2F440_image.jpg&hash=79ba179c6e3c4fd28c9541b948c1499deea50f48)

[Doc B.]

I have fallen a bit behind on the manual, but it is in the process of getting put together. Should be done not too long after the Thanksgiving weekend.

[Doc B.]

OK, I just completed the manual! Yeeehaaw! That makes four assembly manuals I have written this year which is, I think, a record. We had one or two resistors that are shared with the Eros phono version, that ran out while we were getting this done. Those will be here in the next day or two and we will be ready to begin shipping.

[ckniker]

On a (somewhat) related topic, how different is the RIAA eq curve from the NAB (or IEC curve) ?

Here's the gist of my question:

Because I don't have an Eros yet (it's been ordered), I've been playing my rewired Otari Mx5050 head outputs through my existing phono stage (MM input) for the last week or so. As one would imagine, the music has been less than stellar.

Is the RIAA curve different enough (from NAB) that I should expect a major improvement when I eventually hook up to an Eros?

Clearly, I understand that there may be many factors in why I'm getting poor sound currently. I'm using 7 1/2 commercially recorded tapes (bought off ebay). My MX5050 has been cleaned but not yet modded (for tape path improvements).

Thanks in advance,
Chris

[Doc B.]

Check out p.166 at the link below:


http://books.google.com/books?id=GnETXiwh94UC&pg=PA165&lpg=PA165&dq=riaa+vs+nab+equalization&source=bl&ots=MHk37lwyE3&sig=JU8TE_078JC-r4W6OOoyYVtXlM0&hl=en&ei=4Z8VS9ixC4PasQOYndiMBA&sa=X&oi=book_result&ct=result&resnum=2&ved=0CAsQ6AEwATgy#v=onepage&q=&f=false

[Paul Joppa]

Here's a plot, which also shows the very low frequency rolloffs for our implementations of the IEC (which calls for infinite gain at DC, not physically realizable).

[ckniker]

That helps to answer my question.

I'm surprised to read that the NAB eq curve has a tape speed (IPS) dependency in it!

Given that I don't see a speed EQ switch on the Eros (aside from NAB/IEC), should I assume that the EQ is optimized to one speed (15 IPS?)?  Or is it a compromise ?

Thanks,
Chris

[Norbert A.]

I am very interested in buying an Eros tape head preamplifier. But looking at the curves and the dependency of tape speed I have no idea what will happen when playing a prerecorded tape at 3 3/4 ips (there are some in my collection).
Is 3 3/4 ips similar to 7 1/2 or 15 ips?
Norbert

[Paul Joppa]

The Eros is set up to play IEC and CCIR tapes at 15ips, and NAB tapes at 7.5 or 15ips (the equalization is the same for NAB at 7.5 and 15ips). It does not (in stock form) support 3.75 in either NAB or IEC. Other standards not supported in stock form are AES or IEC at 30ips, MRL, or Nagra Master at 15ips.

It has a 2-position switch, so you can get any two of those options - it would be easy to make a setup for NAB at 3.75 and 7.5 or 15ips, with no IEC support, for example. If you are an advanced amateur you might be able to fit a different (very small!) rotary switch with more positions.

We chose these because most available commercial tapes are 7.5ips NAB, and we needed to support the Tape Project tapes at 15ips IEC. For a full suite of equalizations I would probably use a different layout, leaving room for a shielded switch box to contain the equalization options. The same applies to non-RIAA phono equalizations, which some with archives of early recordings might wish for.

[johnsonad]

Hello again Doc and Paul,

Have a couple more questions in regards to the Eros Tape.

1.  I'm using an Otari with standard 2 and 4 track heads direct output.  Does the Eros have enough gain by itself or should I mate it with a head amp or step-up trannies?

2.  If it has plenty of gain in your experience with the Otari, can it be set up from the factory with proper input impedance to match the direct out and stock playback heads?

Thank you in advance.

Aaron

[Doc B.]

The Eros tape head preamp has enough gain for the MX 5050 at 50dB, and the stock input impedance is fine. For what it's worth we've had lousy luck trying to get a step up transformer to work with a tape head.

[johnsonad]

Wow Doc, that was fast and just what I wanted to hear.  For some reason I was under the impression that you needed to measure and match the output impedance of the playback heads, thanks for clearing that up.